1 /* 2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 3 * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice unmodified, this list of conditions, and the following 11 * disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * $DragonFly: src/lib/libthread_xu/thread/thr_list.c,v 1.5 2006/03/12 12:25:57 davidxu Exp $ 28 */ 29 30 #include <sys/cdefs.h> 31 #include <sys/types.h> 32 #include <sys/queue.h> 33 34 #include <stdlib.h> 35 #include <string.h> 36 #include <pthread.h> 37 38 #include "thr_private.h" 39 #include "libc_private.h" 40 41 /* #define DEBUG_THREAD_LIST */ 42 #ifdef DEBUG_THREAD_LIST 43 #define DBG_MSG stdout_debug 44 #else 45 #define DBG_MSG(x...) 46 #endif 47 48 /* 49 * Define a high water mark for the maximum number of threads that 50 * will be cached. Once this level is reached, any extra threads 51 * will be free()'d. 52 */ 53 #define MAX_CACHED_THREADS 100 54 55 /* 56 * We've got to keep track of everything that is allocated, not only 57 * to have a speedy free list, but also so they can be deallocated 58 * after a fork(). 59 */ 60 static TAILQ_HEAD(, pthread) free_threadq; 61 static umtx_t free_thread_lock; 62 static umtx_t tcb_lock; 63 static int free_thread_count = 0; 64 static int inited = 0; 65 static u_int64_t next_uniqueid = 1; 66 67 LIST_HEAD(thread_hash_head, pthread); 68 #define HASH_QUEUES 128 69 static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 70 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 12) % HASH_QUEUES) 71 72 static void thr_destroy(struct pthread *curthread, struct pthread *thread); 73 74 void 75 _thr_list_init(void) 76 { 77 int i; 78 79 _gc_count = 0; 80 _thr_umtx_init(&_thr_list_lock); 81 TAILQ_INIT(&_thread_list); 82 TAILQ_INIT(&free_threadq); 83 _thr_umtx_init(&free_thread_lock); 84 _thr_umtx_init(&tcb_lock); 85 if (inited) { 86 for (i = 0; i < HASH_QUEUES; ++i) 87 LIST_INIT(&thr_hashtable[i]); 88 } 89 inited = 1; 90 } 91 92 void 93 _thr_gc(struct pthread *curthread) 94 { 95 struct pthread *td, *td_next; 96 TAILQ_HEAD(, pthread) worklist; 97 98 TAILQ_INIT(&worklist); 99 THREAD_LIST_LOCK(curthread); 100 101 /* Check the threads waiting for GC. */ 102 for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) { 103 td_next = TAILQ_NEXT(td, gcle); 104 if (td->terminated == 0) { 105 /* make sure we are not still in userland */ 106 continue; 107 } 108 _thr_stack_free(&td->attr); 109 if (((td->tlflags & TLFLAGS_DETACHED) != 0) && 110 (td->refcount == 0)) { 111 THR_GCLIST_REMOVE(td); 112 /* 113 * The thread has detached and is no longer 114 * referenced. It is safe to remove all 115 * remnants of the thread. 116 */ 117 THR_LIST_REMOVE(td); 118 TAILQ_INSERT_HEAD(&worklist, td, gcle); 119 } 120 } 121 THREAD_LIST_UNLOCK(curthread); 122 123 while ((td = TAILQ_FIRST(&worklist)) != NULL) { 124 TAILQ_REMOVE(&worklist, td, gcle); 125 /* 126 * XXX we don't free initial thread, because there might 127 * have some code referencing initial thread. 128 */ 129 if (td == _thr_initial) { 130 DBG_MSG("Initial thread won't be freed\n"); 131 continue; 132 } 133 134 _thr_free(curthread, td); 135 } 136 } 137 138 struct pthread * 139 _thr_alloc(struct pthread *curthread) 140 { 141 struct pthread *thread = NULL; 142 struct tls_tcb *tcb; 143 144 if (curthread != NULL) { 145 if (GC_NEEDED()) 146 _thr_gc(curthread); 147 if (free_thread_count > 0) { 148 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 149 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) { 150 TAILQ_REMOVE(&free_threadq, thread, tle); 151 free_thread_count--; 152 } 153 THR_LOCK_RELEASE(curthread, &free_thread_lock); 154 } 155 } 156 if (thread == NULL) { 157 thread = malloc(sizeof(struct pthread)); 158 if (thread == NULL) 159 return (NULL); 160 } 161 if (curthread != NULL) { 162 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 163 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 164 THR_LOCK_RELEASE(curthread, &tcb_lock); 165 } else { 166 tcb = _tcb_ctor(thread, 1 /* initial tls */); 167 } 168 if (tcb != NULL) { 169 memset(thread, 0, sizeof(*thread)); 170 thread->tcb = tcb; 171 } else { 172 thr_destroy(curthread, thread); 173 thread = NULL; 174 } 175 return (thread); 176 } 177 178 void 179 _thr_free(struct pthread *curthread, struct pthread *thread) 180 { 181 DBG_MSG("Freeing thread %p\n", thread); 182 if (thread->name) { 183 free(thread->name); 184 thread->name = NULL; 185 } 186 /* 187 * Always free tcb, as we only know it is part of RTLD TLS 188 * block, but don't know its detail and can not assume how 189 * it works, so better to avoid caching it here. 190 */ 191 if (curthread != NULL) { 192 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 193 _tcb_dtor(thread->tcb); 194 THR_LOCK_RELEASE(curthread, &tcb_lock); 195 } else { 196 _tcb_dtor(thread->tcb); 197 } 198 thread->tcb = NULL; 199 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 200 thr_destroy(curthread, thread); 201 } else { 202 /* 203 * Add the thread to the free thread list, this also avoids 204 * pthread id is reused too quickly, may help some buggy apps. 205 */ 206 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 207 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 208 free_thread_count++; 209 THR_LOCK_RELEASE(curthread, &free_thread_lock); 210 } 211 } 212 213 static void 214 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 215 { 216 free(thread); 217 } 218 219 /* 220 * Add an active thread: 221 * 222 * o Assign the thread a unique id (which GDB uses to track 223 * threads. 224 * o Add the thread to the list of all threads and increment 225 * number of active threads. 226 */ 227 void 228 _thr_link(struct pthread *curthread, struct pthread *thread) 229 { 230 THREAD_LIST_LOCK(curthread); 231 /* 232 * Initialize the unique id (which GDB uses to track 233 * threads), add the thread to the list of all threads, 234 * and 235 */ 236 thread->uniqueid = next_uniqueid++; 237 THR_LIST_ADD(thread); 238 _thread_active_threads++; 239 THREAD_LIST_UNLOCK(curthread); 240 } 241 242 /* 243 * Remove an active thread. 244 */ 245 void 246 _thr_unlink(struct pthread *curthread, struct pthread *thread) 247 { 248 THREAD_LIST_LOCK(curthread); 249 THR_LIST_REMOVE(thread); 250 _thread_active_threads--; 251 THREAD_LIST_UNLOCK(curthread); 252 } 253 254 void 255 _thr_hash_add(struct pthread *thread) 256 { 257 struct thread_hash_head *head; 258 259 head = &thr_hashtable[THREAD_HASH(thread)]; 260 LIST_INSERT_HEAD(head, thread, hle); 261 } 262 263 void 264 _thr_hash_remove(struct pthread *thread) 265 { 266 LIST_REMOVE(thread, hle); 267 } 268 269 struct pthread * 270 _thr_hash_find(struct pthread *thread) 271 { 272 struct pthread *td; 273 struct thread_hash_head *head; 274 275 head = &thr_hashtable[THREAD_HASH(thread)]; 276 LIST_FOREACH(td, head, hle) { 277 if (td == thread) 278 return (thread); 279 } 280 return (NULL); 281 } 282 283 /* 284 * Find a thread in the linked list of active threads and add a reference 285 * to it. Threads with positive reference counts will not be deallocated 286 * until all references are released. 287 */ 288 int 289 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 290 int include_dead) 291 { 292 int ret; 293 294 if (thread == NULL) 295 /* Invalid thread: */ 296 return (EINVAL); 297 298 THREAD_LIST_LOCK(curthread); 299 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 300 thread->refcount++; 301 } 302 THREAD_LIST_UNLOCK(curthread); 303 304 /* Return zero if the thread exists: */ 305 return (ret); 306 } 307 308 void 309 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 310 { 311 THREAD_LIST_LOCK(curthread); 312 _thr_ref_delete_unlocked(curthread, thread); 313 THREAD_LIST_UNLOCK(curthread); 314 } 315 316 void 317 _thr_ref_delete_unlocked(struct pthread *curthread, struct pthread *thread) 318 { 319 if (thread != NULL) { 320 thread->refcount--; 321 if ((thread->refcount == 0) && thread->state == PS_DEAD && 322 (thread->tlflags & TLFLAGS_DETACHED) != 0) 323 THR_GCLIST_ADD(thread); 324 } 325 } 326 327 int 328 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 329 int include_dead) 330 { 331 struct pthread *pthread; 332 333 if (thread == NULL) 334 /* Invalid thread: */ 335 return (EINVAL); 336 337 pthread = _thr_hash_find(thread); 338 if (pthread) { 339 if (include_dead == 0 && pthread->state == PS_DEAD) { 340 pthread = NULL; 341 } 342 } 343 344 /* Return zero if the thread exists: */ 345 return ((pthread != NULL) ? 0 : ESRCH); 346 } 347